Polydimethylsiloxane encapsulated CsPbBr3 quantum dots enable amplified spontaneous emission-driven in-situ, ultrahigh-speed monitoring of water-soluble food additives

All-inorganic lead halide perovskite quantum dots (PQDs) exhibit outstanding photoluminescence (PL) for optical sensing, yet their severe instability in aqueous environments critically undermines reproducibility and sensitivity. Here, we develop waterproof PQD-based films that maintain 99.8% PL intensity after 2-hour water immersion, overcoming the longstanding hydration-induced degradation challenge. Notably, the films demonstrate amplified spontaneous emission (ASE) with an ultralow threshold of 1.72 μJ/cm2, achieving emission intensity one order of magnitude stronger than conventional PL. Leveraging these impressive properties, we pioneer an ASE-driven optical platform for in-situ monitoring of water-soluble food additives. As a proof of concept, by selecting tartrazine as the detection object, ultrahigh-speed detection at 108 fps is obtained with superior linearity (R2 = 0.999, 0–3.5 μM) for additive concentration quantification, which is unaccessible via existing PL methods under identical experimental conditions. This work establishes a paradigm shift for perovskite-based sensors by transforming material instability into a stabilized photonic advantage.